The prismatic beam concentrator is the subject of a copending application Ser. No. 649,577, filed Sept. 12, 1984 by this inventor.
Prior art includes the following patents:
1. Collimating System, U.S. Pat. No. 2,405,960, 8/20/46, E. H. Land. This device uses a single prism to enlarge and collimate a beam.
2. Luminous Flux Diverging Apparatus Using Prisms, Japan Pat. No. 119,260, 9/17/79, Kazuo Sanagi. This apparatus uses four single prisms to produce a concentrated sheet beam.